comments by ‘zhihua’
对于ASR9000来说 ：
“show interfaces” and “show policy-map interfaces” show L2 frame size.
“show interfaces” does not include FCS bytes, but “show policy-map interfaces” includes FCS bytes(SIP700是个例外)
L1 frame size 和 L2 frame size
如上图就是一个以太网帧的物理层具体所包含的内容。
- Preamble: 前同步码 7 bytes
- SFD: start frame delimiter 1 byte 帧开始定界符
- Dst MAC: 6 bytes
- Src MAC: 6 bytes
- EtherType: 2 bytes
- FCS(CRC): 4 bytes